THIS INVENTION relates to a screening arrangement. The invention relates in particular to a screening arrangement for screening particulate materials such as mineral ores. More particularly the invention relates to screening panels and to screen decks.
The applicant is aware of screening arrangements which are of a modular configuration comprising a plurality of panels which are releasably secured in a side-by-side relationship on a support frame to thereby form a screen deck. It is also known to the applicant that more than one such screen deck can be provided the one above the other so that material to be screened which passes through the upper screen deck can fall onto the lower screen deck to be screened further so that thereby progressively finer particles can be removed from the material being screened.
It is an object of the invention to provide a screening arrangement which includes more than one screen deck above each other, which is compact and which has as few components as possible.
According to the invention there is provided a screening panel predominantly of a synthetic plastics material and having a screening surface in which screening apertures are provided and having securing means adapted to secure the panel releasably in a side-by-side relationship with similar panels, the panel including at least one spacer element along one peripheral edge of the panel and extending in a direction transverse to the screening surface of the panel and being integral and unitary with the panel so that in side view the panel is substantially L-shaped, the spacer element being adapted to space the screening surface of the panel from a second screening surface substantially parallel to the screening surface of the panel so that screened material passing through one of the screening surfaces can fall onto the other screening surface to be screened further by that screening surface.
The spacer element may be adapted to support the second screening surface above the screening surface of the panel so that the screening surface of the panel is spaced below the second screening surface. In this arrangement the securing means on the screening panel may comprise a plurality of deformable spigot-like protrusions spaced from each other along the peripheral region of the panel. The protrusions may be adapted to fit in pairs with the protrusions of an adjacent similar panel in complementary spaced apertures in a support frame. The protrusions may be solid. Alternatively, the protrusions may be half-tubular so that when such protrusions are fitted in pairs in the apertures of a support frame the protrusions form tubular bores into which securing pins may be fitted to spread the protrusions to engage the support frame.
Further securing means may be provided at the free end of the spacer element adapted to releasably secure further screening panels forming the second screening surface to the screening panel so that the second screening surface is positioned above the screening surface of the panel. The securing means at the free end of the spacer element may include a plurality of spaced blind bores.
A sloping ridge may be provided at the side of the screening panel remote from and parallel to the spacer element.
In an alternative arrangement, the spacer element may be adapted to space the screening surface of the screening panel above the second screening surface. In this arrangement the securing means on the screening panel may comprise spaced apertures along an edge of the panel and complementary apertures of the panel, and securing pins adapted to be removably inserted into the aligned apertures to secure the panel to the spacer element.
Further securing means may be provided at the free end of the spacer element adapted to releasably secure the spacer element and thus the panel to a support frame. The securing means on the spacer element may be protrusions adapted to releasably engage complementary apertures in the support frame.
The securing means on the spacer element may be adapted to secure a further set of screening panels forming the second screening surface to the support frame.
An aperture may be provided in a sideways direction through the spacer element to permit material on the screening surface of the screening panel to flow in a sideways direction through the spacer element.
The invention further extends to a screen deck including at least two decks and a support frame supporting both decks, one deck comprising a plurality of screening panels in accordance with the invention arranged side-by-side, and the other deck comprising a plurality of further screening panels arranged side-by-side, the decks being vertically spaced from each other.
The screening panels in adjacent longitudinal rows of panels in at least one of the decks may be staggered from each other in a transverse direction.
The screening panels may have screening surfaces of synthetic plastics material, the screening panel then being substantially entirely of synthetic plastics material. Alternatively, the screening surface of the screening panel may be of metal in the form of a metal sieve embedded in a surround of synthetic plastics material.